Automatic rip cord timer



E. T. BARRON 2,035,779

AUTOMATIC RIP CORD TIMER March 31, 1936.

Filed Nov. 12, 1934 Patented Mar. 31, 1936 UNITED STATES PATENT OFFICEClaims.

This invention relates to improvements in parachutes, more specificallyin time controlling mechanism by which the event of releasing theparachute is governed, and its objects are as 5 follows:

First, to provide a timer which is capable of being quickly set withoutthe necessity of looking at the timer in order to scrutinize a settingdevice of some sort, said timer, therefore, being capable of being setin the dark, for the purpose of causing the release of a parachute fromits container at a given time within the operating time-range of thedevice, and regardless of Whether or not the person suspended by theparachute remains conscious.

Second, to provide a timer which is capable of being set almost asquickly as the attendant on the aircraft can'move from one passenger tothe next, the setting being accomplished by simply operating the plungera given number of times in order to determine the moment when the ripcord shall be pulled automatically, thereby relieving the wearer of theparachute of the responsibility of pulling the rip cord, which he mightfail to do in time due to fear or excitement, or the loss ofconsciousness.

Third, to provide a, timer which is not necessarily set for automaticoperation at a determined period, but in which the foregoing plunger canbe held down until pressure is either voluntarily or involuntarilyreleased, whereupon an automatic pulling of the rip cord would ensue.

Fourth, to provide a timer in which the chance of making a mistake insetting is reduced to a point of its being negligible, the onlyrequirement being a depression and release of the plunger one or moretimes, thereby initiating as many time-periods representative of thedepressions at the end of which an automatic release of 40 the parachutewill occur.

Fifth, to provide a timer which is inherently simple both inconstruction and operation because of the reduction of the working partsto quite a small number.

Other objects and advantages will appear in the following specification,reference being had to the accompanying drawing in which,

Figure 1 is a longitudinal section of the timer case, the internalmechanism being shown in elevation.

Figure 2 is a cross section taken on the line 22 of Figure 1, all of theparts shown being in the initial position prior to setting the timer foran automatic release.

Figure 3 is a cross section taken on the line 33 of Figure 1,particularly illustrating the cam disc and its actuating springs.

Figure 4 is a cross section taken on the line 4-4 of Figure 1,illustrating the interior of one of the winch heads and the spring forturning the winch in order to wind up the rip cord.

Figure 5 is a detail section taken on the line 55 of Figure 1 especiallyillustrating the rack end of the plunger and the gear wheel operatedthereby.

As has been indicated already, the purpose of the device is to pull therip cord for parachute jumpers. The prevailing practice is for thejumper to count up to a certain number before pulling his rip cord afterleaving an aircraft in flight, thereby to make sure that he has safelycleared the aircraft before releasing the parachute from its containerand so avoid the possibility of its becoming entangled. There have beenaccounts of persons pulling the rip cord prematurely with the resultlast named, and there have also been accounts of persons failing to pullthe rip cord either in time for a safe opening, or none at all as in thecase of the loss of consciousness. When the timer is once set and thenleft alone it will function of its own accord to pull the rip cord atthe end of the time-period for which the setting is made.

In carrying out the invention provision is made of a case I which can beof any suitable material and of any desired pattern. The mode by whichit is adapted to be carried by the jumper is not material to theinvention, the only requirement being that it shall be so related to therip cord that upon the rip cord being wound up within the case theresulting pull will undo the container (not shown) and release theparachute (also not shown). A plate 2 closes the open end of the casethrough which the internal mechanism is inserted in the originalassemblage.

Means 3 permanently secure the plate to the case. The case and platehave confronting bosses 4. A formation 5 in the top of the case (Fig. 1)which includes a laterally enlarged hole 6 (Fig. 2), provides a mountingfor a bearing 1 which is capable of limited rocking because of itspintles 8. There is an opening 9 in the top for the rip cord II]. Asmall hinged door H (Fig. 2) permits access to the interior of the casefor resetting a stop arm later described. A boss l2 on the case I and astandard l3 (or its equivalent) provide bearings.

A shaft l4 runs practically from end to end of the case I, and is fixedin the bosses 4 so that it engagement'with corresponding teeth it on theconfronting sideofa gear wheel 99. The pinion i6 and gear wheel it areloose on the shaft it. The confronting ratchet teeth ill, it are held inmesh by the spring l5, and it is only when the gear wheel i9 is turnedclockwise as in a setting operation, that the teeth it drag over theteeth ll.

It is to be observed that the teeth oi the gear wheel it are of a formdiflerent (Fig. 5) from the teeth of the pinion it (Fig. 2) The latterare spurteeth while the former are more in the na= ture of ratchetteeth.

The gear wheel it is positively turned in the clockwise direction only,this being in the setting operation and by manual efiort. This gearwheel turns counter-clockwise by spring action. The pinion it isintended to turn in the counter clockwise direction only, under the samespring action and by reason of the intermeshing teeth ll, it.

A cam disc it is secured to the gear wheel it) so that the two turn onthe shaft id as a unit. The cam disc has a hollow interior M (Fig. 3).This forms a chamber to contain a coil spring 22. This spring is wound.upon the clockwise turn of the gear wheel it, and its unwindingfurnishes the power for the counter-clockwise turn of the gear wheel isand pinion i6. One end of the spring is attached at 23 to the cam disc.The other end is attached at 26 to the shaft id. A cam 25' (which givesthe disc its name) consists of an enlarged. place on its otherwisecircular periphery. This cam terminates in a ing 26 which isinstrumental in stopping the counter clockwise turn of the cam disc byaction of the spring 22.

A winch 27 is free to rotate on the shaft it. It has two heads, one aratchet 2d. the other one 29 a hollow head. The latter has a closureplate 30 (Fig. 1) by which a coil spring ti (Fig. d) is concealed. Oneend of this spring is attached at 32 to the hollow head, the other endbeing attached at 33 to the shaft i l. One end of the rip cord W isattached to the winch 21 as at 3 5. The rip cord It is intended to bepulled out of the opening 9 as part of the original act of the passengeremplacing the parachute container upon his person.

Pulling out the rip cord unwinds it from the winch 21, the consequentcounter-clockwise rotation winding up the spring 3! (Fig. 4) and storingtension therein for the final operation of rewinding the rip cord, or inother words for the pulling of the rip cord, in order to release theparachute.

Escapement mechanism 35 governs the rate of unwinding of the coil spring22 (Fig. 3). This mechanism comprises a gear 36 in constant mesh withthe pinion It. This gear is carried by a shaft 31 which rotates in theboss l2 and standard I3. It carries an escapement wheel 38. This wheelcooperates with a pallet 39. This pallet is pivoted to the case I in anydesired way. It is actuated by the roller pin 40 of a balance wheel 4|.

At this point it is desired to state that the escapement mechanism 35 isnot intended to be confined to the elements shown and just described.This illustration is provided because of its similarity to the ordinaryescapement mechanism of estates "will not turn." Dne of these bosses isthe abutment for the pressure of a spring it, the inner end of whichpresses against a-combined pinion It and ratchet ill. The ratchet teethare held in a clock. In practice it can be substituted by any simpleform oi fan or weight governor, the specific type of governor beingimmaterial as long as it performs the function of an escapementmechanism capable of retarding the unwinding of the spring 22.

A plunger it is slidably carried by the bearing l. The plunger is inline with the gear wheel is and has a. rack end fit to mesh with theteeth thereof. The rack it stops short oi the smooth terminal it of theplunger, and when the smooth end engages the gear teeth there is noappreciable impediment to the counter-clockwise turning of the gearwheel by unwinding of the spring 22 (Fig. 3). The plunger is capable ofbeing swung out of its perpendicular position so as to disengage thegear and rack teeth, the rocking function of the bearing 6 being forthis purpose. The threaded end 55 carries a button (it and a jam nut ll.The button can be screwed in either direction on the threads (45 andthen locked by means of the nut dl, thereby adjusting the length of thestroke of the plunger, the stroke being limited by the engagement of thejam nut with the bearing '5.

A spring id is attached at its ends to the case i and to the plunger 52for the purpose of tending to keep the plunger against the gear wheelis. This insures the meshing of the rack end 63 with the teeth of thegear wheel when the plunger is depressed. A stop arm dd is carried bythe free end of a leaf spring 58. The spring is secured at hi to theplunger 52. The free end of the stop arm has a, crotch 52. The tendencyof the spring til is to hold the stop arm 69 parallel to the plunger,and when the stop arm assumes the parallel position it is inoperativeinsofar as its stopping function is concerned. The door it is opened inorder to gain access .to the stop arm for the purpose of setting.

When set the crotch of'the stop arm 439 receives a pin hi on one side ofthe cam disc is. The leaf spring ht then assumes the bowed position(Fig. 2), the resistance of the bowed spring being suficient to overcomeany tendency of the coil spring 22 (Fig. 3) to unwind in thecounterclockwise direction.

The lug 5d of a dog 55, constituting detent means, rides the peripheryof the cam disc 20, being held there by a spring 56. The dog is turnablycarried by a slender rod 51 (or its equivalent), mounted in the case l.the dog engaging the ratchet 28 by force of the spring 56 (or by gravityif preferred) to prevent the clockwise unwinding of the spring 3! (Fig.4) and the consequent winding up of the ripcord I0 upon the winch 21until a release of the dog occurs by operation of the cam 25 against thelug 54.

The operation is readily understood. When attaching the parachute to theperson intending to use it, the rip cord I0 is pulled out of the casenearly all the way. This act turns the winch 21 in the counter-clockwisedirection (Fig. 4), thereby unwinding the cord and winding the spring3|. The ratchet 28 moves under the dog 55; later the dog holds the winchin the set position. The stop arm 49 is then placed against the pin 53so as to hold the cam disc 20 in the stopped position, whereupon the ripcord is threaded in the proper way to hold the parachute in itscontainer. The cam disc spring 22 (Fig. 3) is always under tension. Theamount of this tension does not vary a great deal, and the spring neverunwinds fully, "being prevented from doing so by the engagement of thelugs 25, 54 at the end of a releasing operation.

Preparatory to making the jump, either the person wearing the parachuteor the attendant on the aircraft will depress the plunger 42 that numberof times corresponding with the number of seconds which are desired toelapse before the parachute is released. To illustrate: A depression ofthe plunger 42 will give the gear wheel IS a fractional turn in theclockwise direction (Fig. The cam 25 and lug 26 will be advanced alittle farther in the clockwise direction (Fig. 2). The time requiredfor the cam 25 to reach the lug 54 will be, let us say five seconds.Every depression of the plunger 42 will advance the cam 25 and lug 26farther in the clockwise direction so that the time-period for theshifting of the lug 54 is lengthened. The manner of determination of thetime-period is a matter of selection and adjustment because it can beregulated by the initial positioning of the cam 25 with reference to thelug 54 as well as by adjusting thestroke of the plunger 42.

Consider a depression of the plunger 42. The cam disc 20 is turned inthe clockwise direction by the engagement of the rack 43 with the gearwheel IS. The latter will turn in reference to the pinion l6, and whenthe teeth l8 slip over the teeth I! the spring l5 will yield upon thelateral displacement of the pinion IS on the shaft l4. The spring 22 wasinitially placed under tension as described. The depression of theplunger increases thetension just a little. The clockwise turn of thedisc disengages the pin 53 from the stop arm 49 so that the arm assumesan inoperative position parallel to the plunger.

Upon release of the plunger 42 the cam disc 20 is free to turn-in thecounter-clockwise direction (Fig. 3) by force of the spring 22. Theescapement mechanism 35 governs the counterclockwise turn. At the end ofthe determined time-period the cam 25 will ride under the lug 54 andraise the dog 55 from the ratchet 28. The lug 26 abuts the lug 54 sothat there will not be a needless unwinding of the spring 22 andconsequent counter-clockwise turning of the cam disc 20.

Upon release of the ratchet 28 the winch 21 is free to rotate clockwise(Fig. 4) by force of the spring 3i. This winds up the rip cord l0 andcauses the release of the parachute from its container. It was statedthat the plunger 42 could be depressed a number of times in order toincrease the time-period at the end of which the parachute release wouldoccur. An alternate mode of operation is to hold the plunger 42depressed in making the jump, the jumper releasing the plunger when hefinds that he has safely cleared the aircraft. i

In any event it is the release of the plunger 42 following a depressionthereof which starts the operation of the timer, the time range beingdetermined according to either of the two modes set out, first one ormore depressions of the plunger and a final release thereof, second asustained depression of the plunger and final release thereof.

I claim:-

1. In a rip cord timer, detent means to be displaced from a detainingposition, a cam disc having a cam which is movable toward the ,detentmeans for its displacement, a pin which is fixed on the disc hence goeswith the cam, a stop arm in blocking engagement with the pin to preventmovement of the disc and cam, a plunger by which the stop arm iscarried, a depression of the plunger releasing the stop arm from the pinso as to free the disc and cam, and a spring which is active upon thedisc to move its cam toward and under the detent means after the reliefof depression of the plunger.

2. In a rip cord timer, detent means to be displaced from a detainingposition, a cam disc.

having a cam which is movable toward the detent means for itsdisplacement, a pin which is fixed on the disc hence goes with the cam,a stop arm in blocking engagement with the pin to prevent movement ofthe disc and cam, a plunger by which the stop arm is carried, adepression of the plunger releasing the stop arm from the pin so as tofree the disc and cam, a spring which is active upon the disc to moveits cam toward and under the detent means after the relief of depressionof the plunger, and lugs respectively on the detent means and cam disc,coming into engagement when displacement is accomplished so as to keepthe cam from going farther.

3. In a rip cord timer, detent means which is displaceable from adetaining position, a disc having a cam, a spring tending to turn thedisc and move the cam toward the detent means for its displacement, apin on the disc, a stop arm having a crotch in which the pin is rested,a plunger and means operable by a depression of the plunger to turn thedisc counter to the spring and displace the pin from the crotch, and aleaf spring by which the stop arm is attached to the plunger, saidspring assuming a bowed position when said arm holds the pin butstraightening beside the plunger upon said displacement of the pin.

4. In a rip cord timer, a case, detent means within the case assuming adetaining position, a cam disc to displace the detent means, said dischaving a gear wheel, a spring tending to turn the disc so that the camwill release the detent means, a stop device to initially preventturning of the disc, a plunger by which the stop device is carried, saidplunger having a rack operable on the gear wheel during one direction ofmovement only during which'the stop device is released. and a rockingbearing for the plunger, being rockably carried by the case to enablethe plunger to swing away from the gear wheel in its idle movement.

5. In a rip cord timer, a spring-actuated winch having arip cordattached thereto, detent means to be displaced from a detaining positionwith respect to said winch, said detent means including a lug, a camdisc having a cam which is movable toward the detent means for itsdisplacement, a pin which is fixed on the disc hence goes with the cam,a stop arm in blocking engagement with the pin to prevent movement ofthe disc and cam, a plunger by which the stop arm is carried, adepression of the plunger releasing the stop arm from the pin so as tofree the disc and cam, a spring which is active upon the disc to moveits cam toward and under the lug of the detent means after the relief ofdepression of the plunger to release the spring-actuated winch forwinding the rip cord, and 9. lug on the cam disc coming into engagementwith the detent lug when displacement is accomplished so as to keep thecam from going farther.

EDWARD T. BARRON.

